A phased array antenna is an array of antennas in which a relative phase of signals feeding the antennas is varied such that an effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions to provide electronic steering of a beam. To convert a reflector array into a beam steerable antenna, a phase shift distribution provided by spatial phase shifting pixels must be dynamically changed depending on the direction of the desired output beam in the far field. Conventionally, this is achieved by changing a capacitance provided by capacitive patches by loading them with varactors or switches.